Earthworm extracts and dry earthworm powders have been used from ancient times in mainly oriental countries as prophylactic agents and therapeutic agents for various diseases, and examples of their uses so far known include uses as bladder-stone-reducing agents and bladder-stone-excretion-promoting agents, therapeutic agents for icterus, oxytocics, tonics, hair-growing agents, aphrodisiacs, antipyretics, therapeutic agents for convulsion, blood circulation promoters, therapeutic agents for hemiplegia, indirect analgesics, diuretics, therapeutic agents for bronchial asthma and therapeutic agents for hypertension.
However, earthworms, which are kept and bred in cultivation beds, contain toxic elements such as mercury, cadmium, lead and arsenic and pathogenic microorganisms even if carefully selected feeds are given to the earthworms. If these toxic substances are ingested by earthworms and accumulated in their bodies during cultivation, drinking of a therapeutic agent produced from the living bodies of the earthworms may adversely affect a human body.
Therefore, when an agent for oral administration is prepared using living bodies of earthworms as a raw material, these toxic substances must be eliminated, and many methods therefor has been proposed. Examples of the methods proposed so far include methods wherein the living bodies of earthworms are soaked in an aqueous solution of an alkali salt such as a sodium salt or a potassium salt to cause excretion of castings in the digestive tract, followed by wet grinding of the earthworms and vacuum-freeze-drying of the resulting suspension, to produce dry earthworm powder useful as a therapeutic agent for diabetes mellitus, an anti-hyperlipemic agent or an agent for blood pressure regulation (see Patent Documents 1 to 4); and a method wherein the living bodies of earthworms are left to stand in an aqueous solution of an acid kept at 6 to 26° C. for 0.1 to 5 hours to eliminate castings in the digestive tract, followed by grinding the earthworms, degassing the resulting ground product, and then vacuum-drying the degassed product while increasing the temperature in a stepwise manner, to produce a therapeutic agent for patients suffering from thrombosis (see Patent Document 5).
Further, a method wherein, in order to remove or reduce heavy metals and fibrinolytic activity-suppressing substances, and precursors of the platelet-activating factor, dry earthworm powder is made into an aqueous solution and turbid components are removed therefrom, to obtain an aqueous earthworm solution having a turbidity of not more than 1.5 in terms of an absorbance at a wavelength of 700 nm has been proposed (see Patent Document 6).